Various vehicle systems may require an antenna for mobile phones, satellite radio, terrestrial radio, and/or global positioning systems. Providing several antennas on a vehicle is costly and aesthetically displeasing. The antennas are preferably low profile and small in size.
Most Terrestrial communications systems require the transmission and/or reception of vertical polarized signals. Terrestrial communications systems may require reception and transmission of radio frequency (RF) signals in multiple bands. For example, vehicle systems such as mobile phones and remote assistance services transmit and/or receive vertical polarized signals in multiple bands.
Mobile phone and remote assistance services typically require communication in both the Advanced Mobile Phone System (AMPS) and the Personal Communications Services (PCS) bands. A dual band antenna that communicates in both the AMPS (824 to 894 MHz) and PCS (1.85 to 1.99 GHz) bands requires a large frequency separation.
In one method, a patch antenna is used for dual band communication. However, the patch antenna transmits/receives most of its energy perpendicular to the plane of the patch antenna, which is not suitable for terrestrial communications. Additionally, patch antennas are large in size, which is costly and aesthetically displeasing.
In another method, a Planar Inverted-F Antenna (PIFA) is used for dual band communication. While the dual band PIFA transmits/receives vertical polarized signals at both frequencies, the separation between the available frequencies is not suitable for communication in both the AMPS and PCS bands.